the rom built with target "aosp_hammerhead-eng" does not work

Hellow xda!! Nice to meet you!!

this is my first post! and i want to ask a question about building AOSP for my Nexus5.

I have successfully built the android-5.0.1_r1(Lollipop) for my Nexus5.
The output-image(boot,recovery,system..etc) can be flashed and boot successfully.
but the rom is built from the default target "aosp_hammerhead-userdebug" in the command "lunch"
see: i.imgur.com/ax61dgO.png



when i try to build the custom target by typing the custom target name--"aosp_hammerhead-eng",
it also built successfully but the output-image can not boot successfully.
the output-image looks no-porblem...
see: i.imgur.com/3jFsnaM.png

Nexus5 was stopping at the "google" logo

does anyone know the reason? i want to build eng mode for the more debugging info!